This invention relates to novel inhibitors of sex steroid activity, for example to compounds having antagonistic activity on sex steroid receptors. More particularly, the invention relates to certain steroid derivatives having specified side-chains at their 13-position and to metabolites thereof which block androgen action by acting, among other mechanisms, through the androgen receptors, while not activating such receptors in some or all androgen-sensitive tissues. When used to treat or reduce the risk of acquiring androgen-exacerbated diseases, when used to treat or reduce the risk of acquiring diseases related to loss of androgenic stimulation, compounds of the invention which activate androgen receptors in the target tissue may be effective even if they act as androgen antagonists in other tissues. These compounds may be effective even if they activate androgen receptors in tissues other than the target tissues.